Form of hull or float



"Nov. 24, 1931. L. R. GRUMMAN FORM OF HULL OR FLOAT Filed Dec. 27. 1950 FIG.

IN VENTOR Patented Nov. 24-, 1931 UNlTED STATES-PATENT OFFICE Application filed December 27, 1930. Serial No. 505,178.

My invention relates to improvements in ing upon water, too, the V bottom has a tendhulls or floats and more particularly to hulls ency to rock or bounce, which is inherently or floats adapted to be propelled by means dangerous, fpr it occurs just as flying speed of an air screw, as the fiotation member of a is lost and the operator has a minimum of seaplane, flying boat or amphibian airplane. control over his plane. 65

Upon the earliest seaplane hulls with fiat The objects of my invention are to provide bottoms were commonly used, largely bea hull for airplanes adapted to operate from cause less power was required to lift a hull water, which will permit speedy take-off, imof this type from the water. This advanprovemaneuverability,reduce bouncing upon in tage was largely offset, however, by disadalighting, permit the use of less cumbersome 60 vantages in maneuvering or taXiing upon landing equipment when used on amphibian the water, and by the shock attendant upon airplanes, and permit the lowering of the cenalighting. ter of mass without reducing the effective lVith the development of powerful engines ground clearance of such an airplane while 1.; of light weight, the trend of bull design has operating upon land. Other objects are 65 been toward a hull with a llhaped bottom. either obvious or will be pointed out herein- A bottom of V section provides a considerable after. i shock absorbing quality upon alighting on Referring to the drawingaFigure 1 is a or upon taxiing over rough water. On side elevation of a hull in which the invention 7 -34; smooth water the effect is present but, of is incorporated; Figure 2 is a sectional view course, less noticeable. As the power availat the step; and Figure 3 is a perspective of able for airplanes of this type increased, the the bottom surface of the hull turned bottom tendency of hull builders was to increase the up and presenting the rear face of the step. steepness of the V bottom. A bottom in Th h ll has a nose 1, preferably blunted which each side makes a 30 angle to the horito provide an easy entrance into the water, zontal is in general use today. together with ahigh degree of buoyancy.

In order to reduce the suction of the Water A k l 2 2 ay r n the length of the in taking off, one or more steps a e us y hull, following the center line from the nose provided in the bottom, and that part of the b 1 to a t 3, The stem 3 may be 11 bottom to the rear of the step or steps is used to support the tail surfaces of the airsloped upward to keepits surface clear of pla i some ty e of construction. At an water leaving the step. This construction a l upward fr th keel 2, front bottom permits rapid acceleration of the airplane and surfaces 4 d rear botto urfaces 4a slope co q r y take-01f outward to side surfaces 6.

135 Despite the improvements in performance Th f t b tt surfaces 4 and the rear 0f hulls with a V 1301550? a a p, Such bottom surfaces 4a are angularly disposed toconstruction is still unsatisfactory in some d h ther'and are nn cted by a step 7. respects. The V bottom a disadvantage Th 1 11 i Fi 1 i shown i th i when pp to an amphibian airplane for tion it should assume when the airplane it the reason that in order to provide ample supports is at rest upon the water. In this clearance for land operations the landing iti th k l 2 b d upward from the gear must be designed to lift the entire airh i t l t a i t li htl f d f th plane much higher {T0111 ground than tep and Continues as to the Stern 3 followwould be the case with a flat bottomed hull. i th center li f th wardly sloping T makes the airplane g y and 3W1!" rear bottom surfaces 4a heretofore referred ward upon land, where its high center of t gravity is a great handlcap in Cross-Wind A triangular flat bottom surface 5 having maneuvering. The landing gear required to it a at the bend of the keel 2 -2a and provide ample clearance is necessarily heavier extending backward to the step 7 15 formed than one with shorter members. In alightby flattening the bottomsurfaces 4 1ust for- Lid Ward of the step. This triangular flat bottom 5 is preferably in the same plane as the keel 2a, so that the keel 2a is unbroken by the step 7. The latter is divided into port and starboard sections, and by reason of the flat surfaces has a gentle slope at the center line instead of the abrupt break characteristic'of such steps in ordinary practice. This fiatsurface 5 and washed out step 7 relatively central of the hull is responsible for noticeably improved performance when used in conjunction with an airplane. A hull of this type is more easily maneuvered in the water, it leaves the water with :less expenditure of power, and upon alia'hting' has less tendency to rocker bounce. WVhen-aisedouan airplane of the amphibian type, it has the added-advantage of permitting; reasonable ground clearance with comparatively light and short undercarriage members. in an amphibian "the hull, during land .operations. assumes a different .position from-that shown in. Figure 1 with :the heel 2a approximately. parallel to theground. Without the washed out step .7 high .clea ance would have to be provided to protect the pointed .ang leof the step. but withzmvconstruction the sameieifeotive clearance may be obtained without liftingtheentire structure so far from the ground. f he advantages of the lower center of mass and the lighter undercarriage members are readily apparent to anyone skilled in the art.

I do not :desire to limit my invention to the precise embodiment illustrated, but to "include all modifications which come fairly triangular flattened section of the V bottom in the'ricinity of thestep reduoingthe height of the central portion of the step.

4. A float having a forward and rear bottom surfaces in angular relationship, a. keel common to both surfaces, ,a step connecting both surfaces, and a triangular flattened portion of the forward bottom surface on each side of the keel extendin3- back to the step.

5. In :a floathaving greater length than width, fore and aft bottom surfaces in angular relationship to :each other and meeting;

-on the ccnterlline,and a-step having a sloping wedge-shapedcenter connecting'said surfaces across their width.

6. A float having fore and aft bottom surfaces angularly disposed toward each other, a center line at the lowermost portion of said surfaces, and a step aft of the angle of the center line and on both sides thereof connecting the two surfaces, the height of said step diminishing .at said center line.

7.. Afloat having fore .andaft bottom surfaces in angular relationship, a center line common to both surfaces, a flattened portion on the forward surface in the same plane as the .centerline of the rear surface. and a step connecting the rear surface to the forward surface and to the flattened portion.

8. A float having fore and aft bottom sur faces, .a step [connecting said surfaces. said step joining the after surface at approximately a rightangle,:and joining part of the forward surface at approximately a right. :angle, and the balance of a'the forward. surface at an obtuse angle.

9. A float, a plurality :of bottom surfaces on said float, said surfaces being angularly disposed toward each other in fore and aft relationship, heels at the lowermost part of said bottom surfaces, .a step connecting the adjacent en ds'of said surfaces,.said step being flattened at its central part to permit of the extension of the keel :of the rearward surface to meet thekeel .of the forward surface.

L. 'R. GRUMMAN. 

